Marine well drilling method and apparatus

ABSTRACT

Method and apparatus for drilling an underwater well using subsurface wellhead equipment. A landing base is lowered at the lower end of a conductor pipe toward an underwater bottom. A guide frame is positioned above the landing base. A rotary driven tubular member, passed through the guide base is connected to the conductor pipe to drill the conductor pipe into the underwater bottom after the landing base rests on the bottom. The tubular member is removed after the conductor pipe is cemented and a bit is guided into the conductor pipe to drill hole for a surface casing having a mandrel at its upper end to which blowout preventers may be connected by a hydraulically actuated connector.

United States Patent [151 3,672,447

Koiahl 1 June 27, 1972 1 MARINE WELL DRILLING METHOD 2,808,229 10 1057Bauer et al ..175/7 AND APPARATUS 2,808,230 10/1957 McNeill et a1. 175/72,891,770 6/1959 Bauer et al..,. 175/7 [72] Inventor: David C. Koiahl,Bakersfield, Cal1f. 2,923,531 2/1960 Bauer et 31"" I "175/7 [73]Assignee: Richfield Oil Corporation, Los Angeles, 29509 8/1960 NfcolsonwCalif. 5, 42 4/1967 Nicolson 166/6 Filed: p 1963 Primary ExaminerMarvinA. Champion Assistant Examiner-Richard E. F avreau [211 App]' 772888Attorney-Blucher S. Tharp Related U.S. Application Data [57] ABSTRACT[63] Continuation of Ser. No. 628,727, Dec. 17, 1956,

abandoned Method and apparatus for dnllmg an underwater well usingsubsurface wellhead equipment. A landing base is lowered at 52 U.S. c1..l66/.6, 175/7 the end 0f a mducmr Pipe Ward underwater 5] In! CL 7H2Ezlb 43/01 tom. A guide frame is positioned above the landing base. Aro- [58] Field of Search ..175/5-10; 166/.5, drive" tubular memberPassed hmugh the guide base 166/6 connected to the conductor pipe todrill the conductor pipe into the underwater bottom after the landingbase rests on the [56] References Cited bottom. The tubular member isremoved after the conductor pipe is cemented and a bit is guided intothe conductor pipe to N E STATES PATENTS drill hole for a surface casinghaving a mandrel at its upper end to which blowout preventers may beconnected by a hydrauli- 1,4695 74 10/1923 Allan 175/7 X Cally actuatedconnector. 1,691,715 11/1928 Hansen.... 2,476,309 7/1949 Lang 175/8 8Claims, 9 Drawing Figures PATENTEDJUNZ'I m2 SHEET 10F 8 R m @W. Z v 4 ww my 1 a E W fil m PATENTEDJIM? I972 3, 572,447

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A770F/VEY5 MARINE WELL DRILLING METHOD AND APPARATUS This application isa continuation of application Ser. No. 628,727, filed Dec. 17, 1956, nowabandoned.

This invention relates to marine well drilling method and apparatus andis particularly directed to improvements relating to the drilling ofwells in relatively deep water. This invention finds particularusefulness in connection with well drilling installations wherein thewell head equipment is mounted on the ocean floor and wherein the rotarymachine, mast, drawworks and related drilling equipment are mounted on afloating vessel.

It is often necessary or desirable to place a relatively shortlengthlarge-diameter conductor pipe in position on the ocean floor and cementit in place. Similarly, it is often necessary or desirable to extendsurface casing down through the interior of this conductor pipe. Drillpipe used for drilling the well to the desired depth passes through theinterior of the surface casing. One or more blowout preventers andrelated shut-off equipment are placed at the ocean floor and connectedto the upper end of the surface casing. The blowout preventers areremotely controlled from the floating vessel to shut in the well whennecessary to prevent a blowout.

When the water depth is such as to permit divers to work on the oceanfloor, the various steps in placing the conductor pipe, surface casingand connecting the blowout preventers in place at the well head can beaccomplished without serious difficulty. However, when the water depthis too great to permit divers to work at or near the well head on theocean floor serious problems are presented. It is an important object ofthis invention to provide a method and apparatus for accomplishing theabove named steps in relatively deep water and without the use ofdivers. Another object is to provide a novel method for installing wellhead adjacent the ocean floor. Another object is to provide new andimproved apparatus for carrying out the method. Related and moredetailed objects and advantages will appear hereinafter.

In the drawings:

Steps in the preferred method are shown and the preferred form of theapparatus is disclosed.

FIG. I shows a landing base being lowered into position on a conductorpipe.

FIG. 2 shows a conductor pipe supported from the floating vesselwhile asmaller pipe is connected to its upper end.

FIG. 3 is a view taken in the direction 33 as shown in FIG. 2illustrating the landing base in position on the ocean floor and showingthe guide post assembly suspended on guide cables, with the smaller pipepassing through the center of the guide post assembly.

FIG. 4 shows the conductor pipe, landing base and guide post assembly infinal position on the ocean floor.

FIG. 5 shows drilling tools being guided and lowered into the upper endof the conductor pipe, after the conductor pipe has been cemented inplace.

FIG. 6 shows surface casing being lowered into place.

FIG. 7 shows the blowout preventers and related'apparatus in operativeposition adjacent the ocean floor.

FIG. 8 is an enlargement of a portion of FIG. 7.

FIG. 9 is a plan view taken in the direction of the lines 9- -9 as shownin FIG. 3 and illustrating the mounting of the rotary machine on thefloating vessel.

Referring to the drawings, the floating vessel or drilling supportstructure generally designated 10 is provided with a central opening orwell 11 through which drilling operations may be carried on. A landingbase 12 is lowered through this well opening 11 on the lower end of aconductor pipe 13. The conductor pipe has an enlarged hollow bit 14 atits lower end and the central hub 15 of the landing base 12 rests on theshoulder 16 adjacent this bit 14. An elevator 17 of conventional type isoperated by hoisting equipment (not shown) carried on the floatingvessel 10. The elevator is clamped about the conductor pipe 13 above theposition of the laterally projecting lugs 18 which are mounted on theouter surface of the pipe 13. These lugs 18 are too large to passthrough the central opening in the hub 15 of the landing base 12.

As shown in FIG. 2, the conductor pipe 13 is lowered to a position belowthe floating vessel or drilling support structure 10 and means such aschains 19 are employed to suspend the elevator 17 and conductor pipe 13and landing base 12, while a tubular member 20 which in effect forms anupper portion of the conductor pipe, is connected to the upper end ofthe conductor pipe 13. This connection is provided by means of athreaded member 21 engaging left hand threads 22 in the upper end of theconductor pipe 13. While the conductor pipe 13 and tubular member 20 aresupported by means of the chains 19, a guide frame generally designated23 is lowered through the well opening 11 on cables 24. These cables areattached to the upper end of parallel vertical posts 25 which aremounted on the frame 23 and supported from the drilling supportstructure with conventional hoisting equipment, for example, air winchesor counterweights. A central opening 26 on the frame receives thetubular member 20. The lower end of the frame 23 includes a support ring27. This ring is counterbored at 29 to provide clearance for the lugs18. The rotary machine 28 and its subframe 31 are then placed inposition within the well opening 1 1 in the floating vessel 10.

The tubular member 20 passes through the rotary machine 28 which issupported in a novel manner on the floating vessel 10. As best shown inFIG. 9, this rotary machine 28 is mounted on the subfrarne 31 havingaxially aligned supporting trunnions 32 and 33. These trunnions extendin the direction of the longitudinal axis of the floating vessel 10. Therotary machine is positioned centrally over the opening or well 11 whichis provided in the vessel 10. The drive shaft 34 of the rotary machinemay be driven in any desired manner and as shown in the drawings, thisdrive shaft extends through the hollow trunnion 32 from a source ofpower (not shown).

The tubular member 20 is driven by the rotary machine through asplit'drive bushing assembly 35. Thus the tubular member 20 and thebushing assembly 35 constitute means for connecting the conductor pipeto the power means, i.e., the rotary machine 28. Bushing assembly 35 isformed with two duplicate halves clamped around the tubular member 20 bymeans of threaded fastenings 36 to provide power means for rotating theconductor pipe. The upper end of the tubular member 20 is supported by aswivel (not shown) in the conventional manner.

The tubular member 20 is lowered from the drilling support structureuntil the landing base 12 rests on bottom as shown in FIG. 3. The splitbushing 35 is then installed on the tubular member 20 and the rotarymachine is operated to turn the tubular member 20 and conductor pipe 13.In this way the bit 14 is caused to drill into the bottom formation. Afluid such as seawater, may be pumped down the interior of the tubularmember 20 and conductor pipe 13 to bring up cuttings by the action ofthe bit 14. As the hole deepens, drilling operations are interruptedfrom time to time to readjust the position of the split bushing 35 withrespect to the tubular member 20 so that the split drive bushing 35remains in contact with the driving parts of the rotary machine.

When the lugs 18 on the conductor pipe 13 reach the flange 30 on the hub15 of the base member 12, the rotary machine 28 is stopped and cement ispumped down the interior of the tubular member 20 and through theinterior of the conductor pipe 13. The cement emerges at the bit 14 andreturns to the level of the ocean floor 37 through the bore hole 38formed by bit 14. Overflow from the bore hole 38 may fill in around thelanding base 12 and assist in anchoring it to the ocean floor 37.

After an elapse of time to permit the cement to set up," the rotarymachine is again caused to supply torque to the upper end of the tubularmember 20. Since the conductor pipe 13 is cemented solidly in place, theconductor pipe does not turn and the result is that the left handthreads 22 are disconnected to separate the tubular member 20 from theconductor The tubular member 20 is then withdrawn upwardly through therotary machine and a drill string 39 is reinserted through the rotarymachine 28. The upper end of this drill string is provided with a squarekelly 40 which is engaged with the usual kelly bushing (not shown). Thelower end of this drill string 39 is provided with a conventional bit41. A cross head guide 42 is provided in order to guide the bit 41 intothe upper end of the conductor pipe 13. This guide includes a pair oflaterally spaced tubular elements 43 adapted to slide freely on thecables 24 and posts 25. The guide 42 is provided with a central opening44 which loosely receives the drill string 39 and during the operationof lowering the guide into position on the post 25, the guide rests on ashoulder 45 provided on the drill string 39 just above the bit 41. Theopening 44 is large enough to pass tool joint couplings and rubberprotectors on the drill string 39. After the bit 41 has been guided intothe conductor pipe 13, the usual rotary drilling operations are carriedout to drill out the cement in the interior of the conductor pipe 13 andto form a bore hole extending into the formation below the bit 14. Thisbore hole 46 does not extend into the production zone but is only deepenough to set surface casing 47. Seawater may conveniently be used forcirculating the cuttings out from the bit 41.

After the bore hole 46 has been completed, the surface cas ing 47 islowered into position using the cross head guide 42 for piloting thelower end of the easing into the conductor pipe 13. The lower end of thecasing 47 is then cemented in position by pumping cement down throughthe interior of the casing and allowing it to fill the annular spacebetween the casing 47 and the bore hole 46.

A mandrel 48 is connected to the casing and forms the upper portionthereof. This mandrel 48 has a downwardly facing shoulder 49 which restson the upper end of the conductor pipe 13. The upper end of the mandrelis provided with a left hand thread 50 which is disengaged from theupper portion of the casing string after the lower portion of the casinghas been cemented in place. The upper portion, not shown, of the easingstring is then withdrawn upwardly. The parts are then in a position asshown in FIG. 7. The weight of the casing 47 rests on the conductor pipe13 and the weight is carried by the lugs 18 resting on the flange 30ofthe landing base 12.

The preliminary operations for drilling of the main well bore are nowcomplete. A blowout preventer assembly generally designated 52 is thenlowered into position as shown in FIG. 7. This assembly 52 includes aremote controlled gate valve 53, double gate valve member 54 and a pairof blowout preventers 55 and 56. A spool 57 connects the parts 52 and53. Assembly 52 also includes a pair of parallel tubular elements 58which slidably receive the cables 24 and posts 25. Assembly 52 islowered as a unit until the gate valve member 53 which is a conventionalgate valve having sliding elements, rests on the upwardly facingshoulder 59 on the mandrel 48. Horizontally movable elements 60 on thevalve member 53 are then closed about the mandrel below the abutment 61.The movement of the ram elements 60 is controlled by means of thehydraulic lines 62 which extend to the floating vessel 10. When the rams60 are closed, the blowout preventer assembly 52 is latched and sealedwith respect to mandrel 48 which forms the upper end of the surfacecasing 47.

A drill string 63 having a conventional bit 64 on its lower end is thenguided by means of the cross head guide 42 into the central openingwhich extends through the blowout preventer assembly 52. The bit 64 anddrill string 63 pass downward through the blowout preventers 56, 55 andthrough the valve member 54 and 53 and downward through the interior ofthe mandrel 48 and surface casing 47. Sealing pans (not shown) withinthe blowout preventers 55 and 56 contact the outer surface of the drillstring 63 to form a seal. Accordingly, when fluid is circulated downwardthrough the drill string 63 and out through the bit 64 in theconventional manner, this mud fluid passes upward through the annulusbetween the drill string 63 and casing 47 and through the interior ofthe mandrel 48, gate valve members 53 and 52 and blowout preventers 55and 56. The mud fluid then passes outward through the mud return lines65 which extend to the floating vessel 10. The well is then drilled inthe conventional manner using the drill string 63 and operating throughthe blowout preventer assembly 52. Each time that the drill string 63 iswithdrawn to change the bit 64, the cross head guide 42 serves as apilot for guiding the bit back into the blowout preventer assembly 52.Hydraulic lines in the form of hoses are provided for each of themembers 52, 55 and 56 for the purpose of actuating closure pans thereinby remote control from the floating vessel 10.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth, but my inventionis of the full scope of the appended claims.

What is claimed is:

1. The method of drilling a well in an underwater location from adrilling support structure, comprising the steps of:

lowering a landing base from said support structure by means of ashouldered conductor pipe to rest the landing base on the bottom, theconductor pipe having a bit at its lower end,

drilling a portion of the conductor pipe into the bottom formation fromsaid support structure,

lowering from said support structure an apertured guide frame by meansof a pair of cables over the upper end of the conductor pipe to rest onthe landing base,

guiding drilling tools from said support structure into the upper end ofthe conductor pipe extending therethrough into the formation by means ofsaid cables, and

operating the drilling tools from said support structure to form a borehole therein extending below the lower end of said conductor pipe.

2. The method of drilling a well in an underwater location from afloating vessel, comprising the steps of:

lowering a landing base from the vessel by means of a shoulderedconductor pipe to rest the landing base on bottom, the conductor pipehaving a bit at its lower end,

drilling a portion of the conductor pipe into the bottom formation bymeans of a tubular member connected to said conductor pipe and extendingfrom the vessel,

lowering an apertured guide frame by means of a pair of cables extendingfrom the vessel over the tubular member and over the upper end of theconductor pipe to rest on the landing base,

disconnecting said tubular member from said conductor pipe,

guiding drill tools into the upper end of the conductor pipe by means ofsaid cables extending between the vessel and the frame, and

operating the drill tools from the vessel to form a bore hole extendingbelow the lower end of said conductor pipe.

3. The method of drilling a well in an underwater fonnation from afloating vessel, comprising the steps of:

lowering a landing base from the vessel by means ofa shoulderedconductor pipe to rest the landing base on bottom. the conductor pipehaving a bit at its lower end,

drilling a portion of the conductor pipe into the bottom formation bymeans of a tubular member extending from the vessel,

cementing said conductor pipe into said formation,

lowering an apertured guide frame by means of a pair of cables extendingfrom the vessel over the tubular member and over the upper end of theconductor pipe to rest on the landing base, disconnecting said tubularmember from said conductor guiding drilling tools into the upper end ofthe conductor pipe by means of said cables extending between the vesseland the frame,

operating the drilling tools from the vessel to form a bore hole,

lowering and guiding casing into the bore hole through said conductorpipe with the upper end of the casing resting upon the conductor pipeand protruding above the frame, lowering a blowout preventer assemblyover said cables into position on said frame guide means wherein amember of said assembly encompasses the upper protruding end of thecasing,

lowering drilling tools from said vessel through said blowout preventerto said formation, and

operating drilling tools extending through the blowout preventerassembly and casing to deepen the well.

4. Marine well drilling apparatus including a drill string and powermeans comprising, in combination:

a landing base having an opening and being adapted to rest on the oceanfloor,

a conductor pipe slidably mounted within the landing base opening andhaving stop means on the outer surface thereof resting on the landingbase,

a bit on the lower end of the conductor pipe for drilling the conductorpipe into the formation,

means for connecting said conductor pipe to said power means,

a frame with laterally spaced vertical guide posts associated therewithresting on the landing base and having a central opening into which theupper end of the conductor pipe extends,

an upwardly extending guide cable connected to each of said guide posts,

means for supporting the cables, and

means slidably engaging the cables for guiding said drill string intothe upper end of the conductor pipe.

5. Marine well drilling apparatus including power means comprising, incombination:

a landing base having an opening and being adapted to rest on the oceanfloor,

a conductor pipe slidably mounted within the landing base and havingstop means on the outer surface thereof resting on the landing base,

a bit on the lower end of the conductor pipe for drilling the conductorpipe into the formation,

means for connecting said conductor pipe to said power means,

a frame with laterally spaced vertical guide posts associated therewithresting on the landing base and having a central opening into which theupper end of the conductor pipe extends,

a surface casing extending through the conductor pipe and having amandrel at the upper end thereof, the mandrel having a first shoulderresting upon the upper end of the conductor pipe and at least oneaxially spaced shoulder above said first shoulder, said conductor pipebeing affixed to said formation,

an upwardly extending guide cable connected to each of said guide posts,

means for supporting the cables, and

a blowout preventer assembly having laterally spaced elements associatedtherewith, said elements slidably receiving the guide cables and guideposts,

laterally guided movable parts provided in said blowout preventerassembly, said movable parts being adapted to encompass the upper end ofthe mandrel.

6. Marine well drilling apparatus including power means comprising, incombination:

a landing base having an opening and being adapted to rest on the oceanfloor,

a conductor pipe slidably mounted within the landing base opening andhaving stop means on the outer surface thereof resting on the landingbase,

a bit on the lower end of the conductor pipe for drilling the conductorpipe into the formation,

means for connecting said conductor pipe to said power means,

a frame with laterally spaced vertical guide posts resting on thelanding base and having a central opening into which the upper end ofthe conductor pipe extends,

a surface casing extending through the conductor pipe and having amandrel at the upper end thereof, the mandrel having a first shoulderresting upon the upper end of the conductor pipe, and at least oneaxially spaced shoulder above said first shoulder, said conductor pipebeing affixed to said formation,

an upwardly extending guide cable connected to each said guide posts,

means for supporting the cables,

a blowout preventer assembly having laterally spaced elements associatedtherewith, said elements slidably receiving the guide cables and guideposts,

laterally guided movable parts provided in said blowout preventerassembly, said movable parts being adapted to encompass the upper end ofthe mandrel, and

fluid operated laterally guided movable latch means on said memberengageable with said mandrel.

7. Marine well drilling apparatus including power means comprising, incombination:

a landing base having an opening and being adapted to rest on the oceanfloor,

a conductor pipe slidably mounted within the landing base opening andhaving stop means on the outer surface thereof resting on the landingbase,

a bit on the lower end of the conductor pipe for drilling the conductorpipe into the formation,

means for connecting said conductor pipe to said power means,

a frame with laterally spaced vertical guide posts resting on thelanding base and having a central opening into which the upper end ofthe conductor pipe extends,

a surface casing extending through the conductor pipe and having amandrel at the upper end thereof, the mandrel having a first shoulderresting upon the upper end of the conductor pipe, and at least oneaxially spaced shoulder above said first shoulder, said conductor pipebeing affixed to said formation,

an upwardly extending guide cable connected to each of said guide posts,

means for supporting said cables,

a blowout preventer assembly with laterally spaced elements associatedtherewith, said elements slidably receiving the guide posts,

fluid operated laterally guided movable parts provided in said blowoutpreventer assembly, said movable parts being adapted to latch saidblowout preventer assembly onto the upper end of the mandrel.

8. A method of preparing a well in a formation underwater for wellworking operations, said method comprising:

lowering conduit means from support means downwardly through the waterand positioning said conduit means at least partially within an openingextending downwardly into an underwater formation with an upper end ofsaid conduit means submerged beneath water;

from said support means, conveying cementitious material to a zoneexterior of said conduit means and within said opening;

sealingly cementing at least a portion of said conduit means to wallmeans of the opening in said formation;

guiding a wellhead assembly having a well apparatus passageway extendingtherethrough from said support means toward said conduit means bylowering said wellhead assembly in slidable engagement with flexibleguide means extending downwardly from said support means;

prior to said guiding of said wellhead assembly, providing said flexibleguide means supported by said support means and extending to the generalvicinity of said submerged upper end of said conduit means, with saidupper end of said conduit means being exposed;

axially converging and engaging portions of said wellhead assembly andsaid exposed upper end of said conduit means;

interconnecting said wellhead assembly with said upper end of saidconduit means to establish said well apparatus passageway in sealedcommunication with the interior of said conduit means and tomechanically prevent disconslidable engagement with said flexible guidemeans; and

controlling the well apparatus passageway of said wellhead assembly fromsaid support means whereby said well apparatus passageway may beselectively closed off or opened.

1. The method of drilling a well in an underwater location from adrilling support structure, comprising the steps of: lowering a landingbase from said support structure by means of a shouldered conductor pipeto rest the landing base on the bottom, the conductor pipe having a bitat its lower end, drilling a portion of the conductor pipe into thebottom formation from said support structure, lowering from said supportstructure an apertured guide frame by means of a pair of cables over theupper end of the conductor pipe to rest on the landing base, guidingdrilling tools from said support structure into the upper end of theconductor pipe extending therethrough into the formation by means ofsaid cables, and operating the drilling tools from said supportstructure to form a bore hole therein extending below the lower end ofsaid conductor pipe.
 2. The method of drilling a well in an underwaterlocation from a floating vessel, comprising the steps of: lowering alanding Base from the vessel by means of a shouldered conductor pipe torest the landing base on bottom, the conductor pipe having a bit at itslower end, drilling a portion of the conductor pipe into the bottomformation by means of a tubular member connected to said conductor pipeand extending from the vessel, lowering an apertured guide frame bymeans of a pair of cables extending from the vessel over the tubularmember and over the upper end of the conductor pipe to rest on thelanding base, disconnecting said tubular member from said conductorpipe, guiding drill tools into the upper end of the conductor pipe bymeans of said cables extending between the vessel and the frame, andoperating the drill tools from the vessel to form a bore hole extendingbelow the lower end of said conductor pipe.
 3. The method of drilling awell in an underwater formation from a floating vessel, comprising thesteps of: lowering a landing base from the vessel by means of ashouldered conductor pipe to rest the landing base on bottom, theconductor pipe having a bit at its lower end, drilling a portion of theconductor pipe into the bottom formation by means of a tubular memberextending from the vessel, cementing said conductor pipe into saidformation, lowering an apertured guide frame by means of a pair ofcables extending from the vessel over the tubular member and over theupper end of the conductor pipe to rest on the landing base,disconnecting said tubular member from said conductor pipe, guidingdrilling tools into the upper end of the conductor pipe by means of saidcables extending between the vessel and the frame, operating thedrilling tools from the vessel to form a bore hole, lowering and guidingcasing into the bore hole through said conductor pipe with the upper endof the casing resting upon the conductor pipe and protruding above theframe, lowering a blowout preventer assembly over said cables intoposition on said frame guide means wherein a member of said assemblyencompasses the upper protruding end of the casing, lowering drillingtools from said vessel through said blowout preventer to said formation,and operating drilling tools extending through the blowout preventerassembly and casing to deepen the well.
 4. Marine well drillingapparatus including a drill string and power means comprising, incombination: a landing base having an opening and being adapted to reston the ocean floor, a conductor pipe slidably mounted within the landingbase opening and having stop means on the outer surface thereof restingon the landing base, a bit on the lower end of the conductor pipe fordrilling the conductor pipe into the formation, means for connectingsaid conductor pipe to said power means, a frame with laterally spacedvertical guide posts associated therewith resting on the landing baseand having a central opening into which the upper end of the conductorpipe extends, an upwardly extending guide cable connected to each ofsaid guide posts, means for supporting the cables, and means slidablyengaging the cables for guiding said drill string into the upper end ofthe conductor pipe.
 5. Marine well drilling apparatus including powermeans comprising, in combination: a landing base having an opening andbeing adapted to rest on the ocean floor, a conductor pipe slidablymounted within the landing base and having stop means on the outersurface thereof resting on the landing base, a bit on the lower end ofthe conductor pipe for drilling the conductor pipe into the formation,means for connecting said conductor pipe to said power means, a framewith laterally spaced vertical guide posts associated therewith restingon the landing base and having a central opening into which the upperend of the conductor pipe extends, a surface casing extending throughthe conductor pipe and having a mandrel at the upper end thereof, themAndrel having a first shoulder resting upon the upper end of theconductor pipe and at least one axially spaced shoulder above said firstshoulder, said conductor pipe being affixed to said formation, anupwardly extending guide cable connected to each of said guide posts,means for supporting the cables, and a blowout preventer assembly havinglaterally spaced elements associated therewith, said elements slidablyreceiving the guide cables and guide posts, laterally guided movableparts provided in said blowout preventer assembly, said movable partsbeing adapted to encompass the upper end of the mandrel.
 6. Marine welldrilling apparatus including power means comprising, in combination: alanding base having an opening and being adapted to rest on the oceanfloor, a conductor pipe slidably mounted within the landing base openingand having stop means on the outer surface thereof resting on thelanding base, a bit on the lower end of the conductor pipe for drillingthe conductor pipe into the formation, means for connecting saidconductor pipe to said power means, a frame with laterally spacedvertical guide posts resting on the landing base and having a centralopening into which the upper end of the conductor pipe extends, asurface casing extending through the conductor pipe and having a mandrelat the upper end thereof, the mandrel having a first shoulder restingupon the upper end of the conductor pipe, and at least one axiallyspaced shoulder above said first shoulder, said conductor pipe beingaffixed to said formation, an upwardly extending guide cable connectedto each said guide posts, means for supporting the cables, a blowoutpreventer assembly having laterally spaced elements associatedtherewith, said elements slidably receiving the guide cables and guideposts, laterally guided movable parts provided in said blowout preventerassembly, said movable parts being adapted to encompass the upper end ofthe mandrel, and fluid operated laterally guided movable latch means onsaid member engageable with said mandrel.
 7. Marine well drillingapparatus including power means comprising, in combination: a landingbase having an opening and being adapted to rest on the ocean floor, aconductor pipe slidably mounted within the landing base opening andhaving stop means on the outer surface thereof resting on the landingbase, a bit on the lower end of the conductor pipe for drilling theconductor pipe into the formation, means for connecting said conductorpipe to said power means, a frame with laterally spaced vertical guideposts resting on the landing base and having a central opening intowhich the upper end of the conductor pipe extends, a surface casingextending through the conductor pipe and having a mandrel at the upperend thereof, the mandrel having a first shoulder resting upon the upperend of the conductor pipe, and at least one axially spaced shoulderabove said first shoulder, said conductor pipe being affixed to saidformation, an upwardly extending guide cable connected to each of saidguide posts, means for supporting said cables, a blowout preventerassembly with laterally spaced elements associated therewith, saidelements slidably receiving the guide posts, fluid operated laterallyguided movable parts provided in said blowout preventer assembly, saidmovable parts being adapted to latch said blowout preventer assemblyonto the upper end of the mandrel.
 8. A method of preparing a well in aformation underwater for well working operations, said methodcomprising: lowering conduit means from support means downwardly throughthe water and positioning said conduit means at least partially withinan opening extending downwardly into an underwater formation with anupper end of said conduit means submerged beneath water; from saidsupport means, conveying cementitious material to a zone exterior ofsaid conDuit means and within said opening; sealingly cementing at leasta portion of said conduit means to wall means of the opening in saidformation; guiding a wellhead assembly having a well apparatuspassageway extending therethrough from said support means toward saidconduit means by lowering said wellhead assembly in slidable engagementwith flexible guide means extending downwardly from said support means;prior to said guiding of said wellhead assembly, providing said flexibleguide means supported by said support means and extending to the generalvicinity of said submerged upper end of said conduit means, with saidupper end of said conduit means being exposed; axially converging andengaging portions of said wellhead assembly and said exposed upper endof said conduit means; interconnecting said wellhead assembly with saidupper end of said conduit means to establish said well apparatuspassageway in sealed communication with the interior of said conduitmeans and to mechanically prevent disconnection of said wellheadassembly and said upper end of said conduit means; mechanically andselectively maintaining said interlocking of said wellhead assembly withsaid upper end of said conduit means, with said interlocking beingselectively maintainable until said wellhead assembly is to bedisconnected from said end of said conduit means and raised in slidableengagement with said flexible guide means; and controlling the wellapparatus passageway of said wellhead assembly from said support meanswhereby said well apparatus passageway may be selectively closed off oropened.